Night Mode setting on DVD player and Receiver

My dvd player has a night mode setting and so does my Onkyo 575x. The manual for the DVD player claims that it is for late night view and to be able to listen to the dialog much clearer, my reciever saids in "shortens" the dynamic range ?...My questions is, is it advisable to use these settings ? If so can use both at the same time ?..Does it make the high frequencies brighter and limit the lower end for night viewing ?

This is called by another name of Dynamic Range Compression and is part of the Dolby Digital spec. All it does is squish the dynamic range, so that the loud and quiet bits are on a more even volume. It makes the soundtrack easier to listen to at low volumes, however it's not supposed to be used all the time, only when you need to keep it quiet.

I have this feature ON in my DVD player and I have a hard time determining whether it actually works or not. I've done some comparisons with it on and off and don't seem ot notice a difference which is bad since this was a feature I was looking for. Can anyone vouch that it actually works?
I hear that its better when you have the receiver doing the DRC rather than the player. Maybe that is the problem...I don't have a DD receiver and have to rely on the player's DRC.